LAUSR

Lung cancer is the leading cause of cancer-related deaths worldwide, with ∼15, 000 annual US cases presenting with an aggressive lung adenocarcinoma (LUAD) driven by co-mutations in KRAS and STK11 (KS). Loss of STK11 function in KRAS-driven LUAD dysregulates many cellular processes, including metabolism. Specifically, KS cells become “glutamine addicted” and enhance glutaminolysis to drive proliferation. Recent work from our group revealed pro-oncogenic signaling in KS upon glutamine deprivation. We hypothesize that glutamine scarcity promotes metastatic potential in KS via metabolic rewiring. To test this, we employed a cell culture model of KRAS-driven LUAD with and without STK11 (ΔSTK11). At baseline, ΔSTK11 cells demonstrate a hypermetabolic phenotype associated with enhanced glutamine utilization as assessed by Seahorse mitochondrial stress tests. Unexpectedly, deprivation of glutamine led to the detachment of live ΔSTK11 cells, measured by trypan blue exclusion and annexinV/PI staining, that maintained the ability to re-adhere and proliferate in nutrient replete media. Furthermore, ΔSTK11 cells upregulated anti-apoptotic and EMT marker expression in the absence of glutamine. Invasive capacity was assessed using a spheroid model, and while parental spheroids were unaffected by glutamine deprivation, ΔSTK11 spheroids displayed enhanced ameboid-like single cell invasion. To determine the mechanism(s) underlying this metastatic phenotype, we employed heavy nitrogen labeling, which revealed an upregulation of the hexosamine biosynthetic pathway (HBP) upon glutamine deprivation in ΔSTK11 cells. The HBP is an offshoot of glycolysis that serves as a central hub to regulate many cancer fitness pathways via the production of UDP-GlcNAc - a sugar moiety used for generation of glycosylation intermediates or O-GlcNAcylation. Far western blot analysis validated that ΔSTK11 cells have increased O-GlcNAcylation upon decreased glutamine availability. Treatment with FR054, an inhibitor of the intermediate HBP enzyme, PGM3, decreased metastatic potential of ΔSTK11 cells as measured by anchorage independent survival and 3D-spheroid invasion. These results suggest ΔSTK11 cells utilize the HBP as a protective shunt in response to glutamine deprivation, undermining the potential benefit of glutaminase inhibitors (i.e. “glutamine starvation”) as a therapeutic intervention in KS LUAD patients. Future work aims to further elucidate the role of the HBP in promoting metastasis and to determine the mechanism(s) by which ΔSTK11 cells regulate the HBP. Overall, our data reveal novel insight into the molecular mechanisms altered downstream of STK11 loss linking glutamine metabolism with metastatic potential in KRAS-driven LUAD. Shannon Prior, Logan Sands, Sean Lenahan, Cole Royer, Melissa Scheiber, David Seward, Paula Deming. The hexosamine biosynthetic pathway promotes metastatic potential upon glutamine deprivation in STK11 null KRAS-driven lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5391.